Role of weather factors in the disease development and spread of anthracnose of grape

Field trial was carried out to investigate effects of environment on anthracnose of grape caused by Sphaceloma ampelinum on two successive seasons of 1999 and 2000. Among the epidemiology factors viz., temperature, rainfall and relative humidity were studied on disease development. Further the percent disease index was correlated with previous weeks average of weather parameters. The present study revealed that, the disease development was observed from 2^nd week of August to 2^nd week of September and this period was characterized by decrease in maximum and minimum temperature and increase in maximum and minimum relative humidity followed by Increase in rainfall. Further it indicated highly significant positive correlation between the disease index and rainfall (r = 0.602), maximum and minimum relative humidity (r = 0.801 and 0.936). However, it showed negative correlation with maximum and minimum temperature (r = −0.902 and −0.240).